The U.S. Army has concluded that adding alcohol to that mix is unwise.

But now, with the massacre of 16 Afghan civilians, alcohol has been suggested as a possible causal factor in the killings, along with other stressors. Inquiries into the tragedy are ongoing; the facts remain unclear.

The banning of alcohol in war zones became an issue when the United States military entered combat situations in Muslim countries that frown on drinking, first in Afghanistan and later in Iraq. (Still, alcohol was easy to get in the Green Zone in Baghdad, for example, or in the more tolerant Kurdish areas of northern Iraq.)

The military’s General Order No. 1 prohibits the possession or consumption of alcohol in five countries, including Iraq and Afghanistan. When I embedded with U.S. Army cavalry units operating out of Kandahar Air Field in southern Afghanistan, alcohol was banned for the American soldiers there. Consequently, the pile of empty cans of nonalcoholic beer at the base was routinely the size of a couple of Abrams tanks.

Still, alcohol finds its way onto bases and outposts, either passed from soldiers from other countries, smuggled in from local markets or delivered in care packages from home. Sometimes the alcohol is disguised as mouthwash — usually gin or vodka doctored with blue-green food coloring.

The military has identified the alleged killer in Afghanistan as Staff Sgt. Robert Bales, a 38-year-old father of two who had been wounded twice in combat over the course of four deployments. My colleague James Dao reports that a senior government official said Sergeant Bales had been drinking alcohol before the killings.

“When it all comes out, it will be a combination of stress, alcohol and domestic issues — he just snapped,” the official said.

Sergeant Bales’s attorney has disputed those assertions, telling reporters that the sergeant’s marriage was sound, and he questioned the reports about drinking.

“The military rolled out the feeble ‘he’d been drinking’ excuse as if that would explain why a person goes out and kill 17 civilians. It goes without saying that even the most malicious-minded people aren’t led to murder innocent strangers simply as a result of drinking. What’s more, if he’d drunk more than a couple drinks, it’s unlikely he’d have had the stamina and marksmanship to kill, then haul all these bodies outside.”

In a paper written for an ethics class at the U.S. Army Sergeant Majors Academy, Sergeant Major George W. Kaufman notes that General Order No. 1 prohibits drinking and “all soldiers arriving in country receive a laminated hard copy of these orders along with the rules of engagement. This order makes it clear that US soldiers will not consume alcohol.’’

Sergeant Major Kaufman, who served as a senior enlisted adviser in Iraq, said he was often faced with questions from officers there about the propriety of allowing their soldiers to have a few drinks to wick off the stress or wind down after a tough day.

“The scenario was almost always the same,’’ he wrote. “Fine, outstanding, hard working groups of men just need a break. Insurgents frequently shoot at them. Further, they would state their worry about improvised explosive devices (IEDs) and similar dangers that are common threats inside Iraq.

“I can easily overcome this ethical dilemma,’’ Sergeant Major Kaufman wrote. “The answer is NO!! I prove my thesis by referring to General Order 1 and the Army Values that all enlisted soldiers wear with their dog tags.’’

The army’s Substance Abuse Program also says “alcohol and drug use are detrimental to a unit’s operational readiness and command climate and inconsistent with Army Values and the Warrior Ethos.’’

The U.S. Navy announced two weeks ago that it will soon start giving Breathalyzer tests to some sailors as they arrive for work aboard ships. The new program, which contains other “wellness” provisions, will eventually include the Marine Corps, according to Secretary of the Navy Raymond E. Mabus, who made the announcement in an “all-hands” broadcast to sailors and marines.

An assistant secretary of the navy, Juan Garcia, said a pilot Breathalyzer program in submarine units had yielded a 45 percent decrease in “alcohol-related incidents.’’

In a comment about the program on the navy’s official Web site, a Technician 2nd Class, Eric Smith, was quoted as saying, “We have been moving towards a cleaner, smarter Navy, and I would tell my guys that this is just one more step towards that goal. If you aren’t right, now is definitely the time to get right.”

But there has been substantial pushback — at least online — from active and retired sailors and marines who object to the policy.

“Soon they will ban smoking for health reasons,’’ said a commenter, Chefmark, on the Web site military.com. “Tattoos will be regulated into extinction as well. Perhaps it’s needed in this day and age. Those very icons that define a sailor have become obsolete. The future sailor will be skinny, college educated, sober and smoke free. Yup, time for me to retire.’’

A guest columnist on Foreign Policy magazine’s Best Defense blog issued a scathing critique of the Breathalyzer program, calling it “among the most paternalistic, professionally insulting concepts I’ve seen in all my years of service, and I’m not sure I will submit.’’

The pseudonymous author, described as an active duty naval officer with more than 10 years of service, also said: “Yes, I know my options, and I just may exercise them and go right over the side the first time the duty blowmeister shoves a plastic tube in my face and treats me like a drunk driver for daring to report for duty.’’